Hose

ABSTRACT

An end fitting for terminating an end of a hose including a tubular body of flexible material arranged between inner and outer gripping members, wherein the end fitting includes: an inner member adapted to be disposed at least partially within the hose; a sealing member adapted to seal at least part of the tubular body fully around the circumference between the sealing member and the inner member; and a separate load transfer member adapted to transfer axial loads between the hose and the inner member in such a manner that said axial loads are diverted around the sealing member in order to reduce, or eliminate, the axial load on the hose between the sealing member and the inner member, and wherein the sealing member is adapted to seal against the tubular body independently of the application of axial loads between the hose and the inner member.

This application is a division of U.S. application Ser. No. 10/311,399,filed May 23, 2003, now U.S. Pat. No. 7,243,686 B2, which is a §371 ofPCT/GB01/02562, filed Jun. 12, 2001, and claims priority to thefollowing applications: GB 0111022.0, filed May 4, 2001; GB 0109011.7,filed Apr. 10, 2001; GB 0109012.5, filed Apr. 10, 2001; GB 0109013.3,filed Apr. 10, 2001; GB 0014354.5, filed Jun. 12, 2000; GB 0014355.2,filed Jun. 12, 2000; GB 0014352.9, filed Jun. 12, 2000; GB 0014350.3,filed Jun. 12, 2000; and GB 0014353.7, filed Jun. 12, 2000.

This invention relates to hose, and more particularly relates to hosehaving improved axial strength. The invention is especially concernedwith hose which can be used in cryogenic conditions. The invention alsorelates to an end fitting for a hose, and to a method of making a hose.

Typical applications for hose involve the pumping of fluids from a fluidreservoir under pressure. Examples include supplying of domestic heatingoil or LPG to a boiler; transporting produced oilfield liquids and/orgases from a fixed or floating production platform to the cargo hold ofa ship, or from a ship cargo hold to a land-based storage unit;delivering of fuel to racing cars, especially during refuelling informula 1; and conveying corrosive fluids, such as sulphuric acid.

It is well known to use hose for the transport of fluids, such asliquefied gases, at low temperature. Such hose is commonly used totransport liquefied gases such as liquefied natural gas (LNG) andliquefied propane gas (LPG).

In order for the hose to be sufficiently flexible, any given length mustbe at least partially constructed of flexible materials, i.e., non-rigidmaterials.

The structure of such hose generally comprises a tubular body offlexible material arranged between an inner and outer helically woundretaining wires. It is conventional for the two wires to be wound at thesame pitch, but to have the windings displaced by half a pitch widthfrom one another. The tubular body typically comprises inner and outerlayers with an intermediate sealing layer. The inner and outer layersprovide the structure with the strength to carry the fluid therein.Conventionally, the inner and outer layers of the tubular body comprisefabric layers formed of a polyester such as polyethylene terephthalate.The intermediate sealing layer provides a seal to prevent the fluid frompenetrating the hose, and is typically a polymeric film.

The retaining wires are typically applied under tension around theinside and outside surfaces of the tubular body. The retaining wires actprimarily to preserve the geometry of the tubular body. Furthermore, theouter wire may act to restrain excessive hoop deformation of the hoseunder high pressure. The inner and outer wires may also act to resistcrushing of the hose.

A hose of this general type is described in European patent publicationno. 0076540A1. The hose described in this specification includes anintermediate layer of biaxially oriented polypropylene, which is said toimprove the ability of the hose to resist the fatigue caused by repeatedflexing.

Another hose is described in GB-2223817A. The hose described in thispublication is a composite hose comprising an inner helical metalliccore, a plurality of layers of plastics material fibres and films woundon the core, at least one layer of glass cloth and at least one layer ofaluminium foil disposed adjacent one another and wound onto the plasticsmaterial, and an outer helical metallic former. This hose is said to besuitable for transporting flammable fuels and oils.

Another hose is described in GB-1034956A. The hose described in thisapplication is an electrical hose or conduit, i.e., it is intended forcarrying electrical wires rather than for the transport of fluids. As aresult of this, the considerations involved in the design of this hoseare completely different from the considerations involved in the hosedescribed in EP-0076540A1 and GB-2223817A. The hose described inGB-1034956A comprises:

-   -   (i) an internally arranged helically wound wire;    -   (ii) an extruded neoprene hose surrounding the internal wire;    -   (iii) a braided metal sheath surrounding the neoprene hose;    -   (iv) a nylon cord applied helically to the sheath;    -   (v) a canvas wrapping around the nylon cord and the sheath; and    -   (vi) an outer helically wound wire arranged around the canvas        wrapping.

The braided metal sheath is made to follow the convolutions of the innerwire by temporarily winding a further wire around the sheath duringmanufacture of the hose.

Many applications of hose require the hose to be supported along itslength. This especially applies to the transport of the produced liquidsand/or gases mentioned above. Without additional support, conventionalhose is often incapable of supporting its own weight, or the weight ofthe fluid contained therein.

We have now found a way to improve the load carrying capabilities ofhose, especially the type of hose described in EP-0076540A1, so that itcan be used to carry fluids either without the need for any support atall, or with a much reduced requirement for support. The hose issuitable for both cryogenic and non-cryogenic applications.

We have also found a way to improve the sealing layer in hose of thetype described above.

In hose of the type described in EP0076540A1 it is important that thewires are maintained in the correct position. In general the inner andouter helical wires are longitudinally displaced relative to one anotherby a distance equal to about half a pitch length. This arrangement hasbeen found to provide the best structural integrity. However, one of theproblems with this sort of hose is that repeated flexing can cause thecoils of the wire to be displaced out of the proper alignment.

The present invention also relates to improvement to an outer portion ofthe type of hose described above, i.e., to the portion of the hoseexterior of the tubular body.

The type of hose described in EP0076540A1 is usually formed by thefollowing technique: an inner wire is wrapped around a tubular mandrelto form an inner coil; an inner reinforcing layer is wrapped around thetubular mandrel and the inner coil; a sealing layer is wrapped aroundthe inner reinforcing layer; an outer reinforcing layer is wrappedaround the sealing layer; an outer wire is wrapped around the outerreinforcing layer to form an outer coil; the ends of the hose aresecured by crimping; and the hose is removed from the mandrel.

The present invention also relates to an improvement in the terminationof the ends of the hose.

Broadly, we provide an axial strengthening means for hose, whereby thehose can withstand greater axial tension than has previously beenpossible, without impairing the other properties of the hose.

According to a first aspect of the invention there is provided a hosecomprising a tubular body of flexible material arranged between innerand outer gripping members, wherein the hose further comprises an axialstrengthening means adapted to reduce deformation of the tubular bodywhen the tubular body is subjected to axial tension, and the axialstrengthening means is further adapted to exert a radially inward forceon at least part of the tubular body when axial strengthening means issubjected to axial tensioning.

In a particularly preferred embodiment, the failure strain of thetubular body and the axial strengthening means are within the range of 1to 10%. More preferably the failure strain is in excess of 5% at ambientand cryogenic temperatures.

By means of this arrangement, the axial strengthening means improves theability of the hose to cope with axial stresses, and at the same timecan contribute to the structural integrity of the hose during axialtensioning by pressing against at least part of the tubular body. Inaddition, the materials of the tubular body and the axial strengtheningmeans are advantageously compatible so that they each perform in asimilar manner when in operation, so that no single component issubjected to excessive stresses and strains. This means that thematerials of the tubular body and the axial strengthening means respondto strain in a similar manner. A bend strain (for a cylindricalcomponent) of at least 3% is generally needed for the type of hoseapplications primarily envisaged by the present invention. While,inter-layer slip and the straightening of helically oriented componentswill account for some of this slip, there will still be a resultantstrain in the order of 1% acting on the structural components of thehose wall. This compares to a typical yield strain of 0.2% for metals.

It is particularly preferred that the axial strengthening means is madeof a non-metallic material, especially a plastics material—suitablematerials are discussed in detail below. This is because metallicmaterials are unlikely to have the desired strain characteristics.

It is preferred that the tubular body and the axial strengthening meanscomprise the same material, most preferably ultra high molecular weightpolyethylene (UHMWPE), as described in further detail below.

The tubular body preferably comprises at least one reinforcing layer andat least one sealing layer. More preferably, there are at least tworeinforcing layers with the sealing layer sandwiched therebetween.

Preferably, a further reinforcing layer is provided between the outergripping member and the axial strengthening means.

The ultimate strength of the reinforcing layer(s) is preferably between100 and 700 kN for an 8″ (200 mm) diameter hose. It is preferable thatthe bend strain at failure of the reinforcing layer(s) is in the range2% to 15%. Desirably, further reinforcing layer(s) are the same materialas the axial strengthening means, most preferably UHMWPE.

Preferably the axial strengthening means comprises a generally tubularsheath formed of a sheet of material provided in a tubular shape, suchthat the sheath can maintain the integrity of its tubular shape whensubjected to axial tension. The hose may be provided with two or moretubular sheaths in order to further improve the performance of the hoseunder axial tension.

In a particularly advantageous embodiment the axial strengthening meansis provided in the form of a generally tubular braid. In thisspecification the term “braid” refers to a material which is formed oftwo or more fibres or yarns which have been intertwined to form anelongated structure. It is a feature of braid that it can elongate whensubjected to an axial tension. It is a further feature of braid that,when provided in a tubular form, its diameter will reduce when the braidis subjected to axial tension. Thus by providing a tubular braid aroundthe tubular body, or within the structure of the tubular body, the braidwill exert a radially inward force on at least part of the tubular bodywhen subjected to axial tension.

It is preferred that the entire tubular sheath is provided in the formof the braid. However, it is possible for only one or more parts of thelength of the tubular sheath to be provided in the form of the braid.

It is also preferred that the braid extends all the way around thecircumference of the tubular sheath. However, it is possible for onlypart of the circumference of the tubular sheath to be provided in theform of the braid.

The braid may be provided in a biaxial form (i.e. in which the braid isformed of only two intertwining fibres or yarns) or in a triaxial form(i.e. in which there are also longitudinally extending fibres or yarns,for increased axial strength).

Although it is preferred to provide the axial strengthening means in theform of a braid, it may be provided in other forms which meet thefunctional requirements specified above. Thus, the axial strengtheningmeans may be provided as a suitable arrangement of cords or ropeshelically wrapped around the tubular body.

The materials of construction of the hose should be selected to enablethe hose to perform in the environment for which it is intended. Thus,there is a need for the hose to be able to transport pressurised fluidstherethrough without leakage of the fluid through the walls of the hose.There is also a need for the hose to withstand repeated flexing, and towithstand the axial stresses caused by the combination of the hose andfluid weight. Also, if the hose is intended for use in transportingcryogenic fluids, the materials should be capable of operating atextremely cold temperatures without any significant reduction inperformance.

The main purpose of the or each reinforcing layer is to withstand thehoop stresses which the hose is subjected to during transport of fluidstherethrough. Thus, any reinforcing layer which has the required degreeof flexibility, and which can withstand the necessary stresses, will beadequate. Also, if the hose is intended for transporting cryogenicfluids, then the or each reinforcing layer must be able to withstandcryogenic temperatures.

We prefer that the or each reinforcing layer is formed of a sheet ofmaterial which has been wound into a tubular form by winding the sheetmaterial in a helical manner. This means that the or each reinforcinglayer does not have much resistance to axial tension, as the applicationof an axial force will tend to pull the windings apart. The or eachreinforcing layer may comprise a single continuous layer of the sheetmaterial, or may comprise two or more single continuous layers of thesheet material. However, more usually (and depending on the length ofthe hose) the or each layer of the sheet material would be formed of aplurality of separate lengths of sheet material arranged along thelength of the hose.

In the preferred embodiment each reinforcing layer comprises a fabric,most preferably a woven fabric. The or each reinforcing layer may be anatural or synthetic material. The or each reinforcing layer isconveniently formed of a synthetic polymer, such as a polyester, apolyamide or a polyolefin. The synthetic polymer may be provided in theform of fibres, or a yarn, from which the fabric is created.

When the or each reinforcing layer comprises a polyester, then it ispreferably polyethylene terephthalate.

When the or each reinforcing layer comprises a polyamide, then it may bean aliphatic polyamide, such as a nylon, or it may be an aromaticpolyamide, such as an aramid compound. For example, the or eachreinforcing layer may be a poly-(p-phenyleneterephthalamide) such asKEVLAR (registered trade mark).

When the or each reinforcing layer comprises a polyolefin, then it maybe a polyethylene, polypropylene or polybutylene homopolymer, or acopolymer or terpolymer thereof, and is preferably monoaxially orbiaxially oriented. More preferably, the polyolefin is a polyethylene,and most preferably the polyethylene is a high molecular weightpolyethylene, especially UHMWPE.

The UHMWPE used in the present invention would generally have a weightaverage molecular weight above 400,000, typically above 800,000, andusually above 1,000,000. The weight average molecular weight would notusually exceed about 15,000,000. The UHMWPE is preferably characterisedby a molecular weight from about 1,000,000 to 6,000,000. The UHMWPE mostuseful in the present invention is highly oriented and would usuallyhave been stretched at least 2-5 times in one direction and at least10-15 times in the other direction.

The UHMWPE most useful in the present invention will generally have aparallel orientation greater than 80%, more usually greater than 90%,and preferably greater than 95%. The crystallinity will generally begreater than 50%, more usually greater than 70%. A crystallinity up to85-90% is possible.

UHMWPE is described in, for example, U.S. Pat. Nos. 4,344,908,4,411,845, 4,422,993, 4,430,383, 4,436,689, EP-A-183285, EP-A-0438831,and EP-A-0215507.

It is particularly advantageous that the or each reinforcing layercomprises a highly oriented UHMWPE, such as that available from DSM HighPerformance Fibres BV (a Netherlands company) under the trade nameDYNEEMA, or that available from the US corporation AlliedSignal Inc.under the trade name SPECTRA.

Additional details about DYNEEMA are disclosed in a trade brochureentitled “DYNEEMA; the top performance in fibers; properties andapplication” issued by DSM High Performance Fibers BV, edition 02/98.Additional details about SPECTRA are disclosed in a trade brochureentitled “Spectra Performance Materials” issued by AlliedSignal Inc.,edition 5/96. These materials have been available since the 1980s.

In the preferred embodiment, the or each reinforcing layer comprises awoven fabric formed of fibres arranged in a weft and warp direction. Wehave found that it is particularly advantageous if the or eachreinforcing layer is arranged such that the fabric warp direction is atan angle of less than 20° to the axial direction of the hose; we alsoprefer that this angle is greater than 5°. In the preferred embodiment,the or each reinforcing layer is arranged such that the fabric warpdirection is at an angle of from 10° to 20°, most preferably about 15°,to the axial direction of the hose.

The purpose of the sealing layer is primarily to prevent the leakage oftransported fluids through the tubular body. Thus, any sealing layerwhich has the required degree of flexibility, and which can provide thedesired sealing function, will be adequate. Also, if the hose isintended for transporting cryogenic fluids, then the sealing layer mustbe able to withstand cryogenic temperatures.

The sealing layer may be made from the same basic materials as the oreach reinforcing layer. As an alternative, the sealing layer may be afluoropolymer, such as: polytetrafluoroethylene (PFTE); a fluorinatedethylene propylene copolymer, such as a copolymer of hexafluoropropyleneand tetrafluoroethylene (tetrafluoroethylene-perfluoropropylene)available from DuPont Fluoroproducts under the trade name Teflon FEP; ora fluorinated hydrocarbon—perfluoralkoxy—available from DuPontFluoroproducts under the trade name Teflon PFA. These films may be madeby extrusion or by blowing.

We prefer that the sealing layer is formed of a sheet of material whichhas been wound into a tubular form by winding the sheet material in ahelical manner. As with the reinforcing layers, this means that the oreach sealing layer does not have much resistance to axial tension, asthe application of an axial force will tend to pull the windings apart.The sealing layer may comprise a single continuous layer of the sheetmaterial, or may comprise two or more single continuous layers of thesheet material. However, more usually (and depending on the length ofthe hose) the or each layer of the sheet material would be formed of aplurality of separate lengths of sheet material arranged along thelength of the hose. If desired the sealing layer may comprise one ormore heat shrinkable sealing sleeves (i.e. tubular in form) which arearranged over the inner reinforcing layer.

We prefer that the sealing layer comprises a plurality of overlappinglayers of film. Preferably there would be at least 2 layers, morepreferably at least 5 layers, and still more preferably at least 10layers. In practice, the sealing layer may comprise 20, 30, 40, 50, ormore layers of film. The upper limit for the number of layers dependsupon the overall size of the hose, but it is unlikely that more than 100layers would be required. Usually, 50 layers, at most, will besufficient. The thickness of each layer of film would typically be inthe range 50 to 100 micrometers.

It will, of course, be appreciated that more than one sealing layer maybe provided.

A particularly preferred embodiment of the sealing layer is describedbelow.

The axial strengthening means may also be formed of the same material asthe or each reinforcing layer. Thus, it will be clear that the axialstrengthening means, the or each reinforcing layer and the sealing layermay all be formed from the same basic compound. However, the form of thecompound must be different in order to provide the required function,i.e., the axial strengthening means provides an axial reinforcementfunction, the or each reinforcing layer provides reinforcement againsthoop stresses, and the sealing layer provides a sealing function. Wehave found that the UHMWPE materials are most suitable, particularly theDYNEEMA and SPECTRA products. These material have also been found towork well in cryogenic conditions. The preferred parameters of theUHMWPE (molecular weight range, etc) discussed above in relation to thereinforcing layers, are also appropriate to the axial strengtheningmeans. In this regard is should be noted, however, that the parametersof the UHMWPE used in the axial strengthening means need not be the sameas the parameters of the UHMWPE used in the reinforcing layers.

It would be possible for the axial strengthening means to be providedwithin the layers of the tubular body. However we prefer than the axialstrengthening means is positioned between the tubular body and the outergripping member. In an another preferred embodiment, the axialstrengthening means is provided within the layers of the tubular body,and a further axial strengthening means is also provided between thetubular body and the outer gripping member.

When the hose is intended for cryogenic applications, then it isdesirable to provide insulation over the tubular body. The insulationcould be provided between the outer wire and the tubular sheath and/oroutside the outer wire. The insulation may comprise materialconventionally used to provided insulation in cryogenic equipment, suchas a synthetic foam material. It is preferred that the axialstrengthening means is also provided around the insulating layer tocompress the insulation layers and maintain their structural integrity.The axial strengthening means around the insulation layer is preferablyprovided in addition to the axial strengthening means between the outergripping member and the tubular body. A particular suitable form ofinsulation is provided in further detail below.

According to another aspect of the invention there is provided a hosecomprising a tubular body of flexible material arranged between innerand outer gripping members, wherein the tubular body comprises at leastone reinforcing layer of a woven fabric formed of fibres arranged in aweft and warp direction, characterised in that the or each reinforcinglayer is arranged such that the fabric warp direction is at an angle ofless than 20°, more preferably less than 15°, and most preferably lessthan 10°, to the axial direction of the hose. The hose according to thisaspect of the invention may be provided with any desired combination ofthe additional features described in relation to the hose according tothe first aspect of the invention.

According to another aspect of the invention there is provided a methodof making a hose comprising:

-   -   (a) wrapping a wire around a tubular mandrel to form an inner        coil;    -   (b) wrapping a sheet material around the tubular mandrel and the        inner coil order to provide a tubular body formed of the sheet        material;    -   (c) pulling a tubular axial strengthening sheath over a free end        of the mandrel, so that the mandrel extends within the axial        strengthening sheath, then pulling the axial strengthening        sheath along the mandrel so that it at least partially covers        the tubular body;    -   (d) wrapping a wire around the axial strengthening sheath to        form an outer coil;    -   (e) securing the ends of the hose produced in step (d); and    -   (f) removing the hose from the mandrel.

Preferably the coils and the sheet material are applied under tension inorder to provide the hose with good structural integrity.

Preferably the sheet material in step (b) comprises two reinforcinglayers sandwiching a sealing layer, as described above. In the preferredembodiment, an inner reinforcing layer, in sheet form, is wrappedhelically around the inner coil and the mandrel; then the sealing layer,in sheet form, is wrapped helically around the inner reinforcing layer;then the outer reinforcing layer, in sheet form, is wrapped around thesealing layer. Usually a plurality of sealing layers would be applied.

The tubular axial strengthening sheath may be the same as the axialstrengthening sheath described above, and is preferably a braid.

Preferably the inner and outer coils are applied in a helicalconfiguration having the same pitch, and the position of the coils ofthe outer coil are positioned half a pitch length offset from theposition of the coils of the inner coil.

According to another aspect of the invention there is provided a hosecomprising a tubular body of flexible material arranged between an innerand an outer gripping members, the tubular body serving to transportfluid through the hose and to prevent fluid leakage through the body,characterised in that the hose further comprises a generally tubularbraid disposed around the tubular body.

According to another aspect of the invention there is provided a hosecomprising a tubular body of flexible material arranged between innerand outer gripping members, the tubular body comprising a sealing layersandwiched between an inner and an outer reinforcing layer,characterised in that the sealing layer comprises at least two polymericfilms, one of the films being made of a first polymer and another of thefilms being made of a second polymer different from the first polymer.

In an especially advantageous embodiment, one of the polymeric films isstiffer than the other of the films, whereby a differential yield strainis present in the material properties at the operating temperature andpressure. Preferably the outer film is stiffer than the inner film. Theeffect of this is that in the unfortunate occurrence of a hose burst,there is a controlled failure of the sealing layer such that the stifferouter polymer fails while the more ductile polymer holds the internalpressure for a finite time, allowing the pressure gradually todissipate.

In the preferred embodiment, the maximum strain at failure is in excessof 100% at ambient temperature for the more ductile layer, and is atleast 20% less for the other layer.

Each polymeric film of the sealing layer is preferably a polyamide, apolyolefin or a fluoropolymer.

When the polymeric film of the sealing layer comprises a polyamide, thenit may be an aliphatic polyamide, such as a nylon, or it may be anaromatic polyamide, such as an aramid compound.

We prefer that one of the polymeric films of the sealing layer is apolyolefin and that another of the polymeric films of the sealing layeris a fluoropolymer.

Suitable polyolefins include a polyethylene, polypropylene orpolybutylene homopolymer, or a copolymer or terpolymer thereof.Preferably the polyolefin film is monoaxially or biaxially oriented.More preferably, the polyolefin is a polyethylene, and most preferablythe polyethylene is a high molecular weight polyethylene, especiallyUHMWPE, which is described in greater detail above. The preferredparameters of the UHMWPE (molecular weight range, etc) discussed abovein relation to the reinforcing layers, are also appropriate to thesealing layer. In this regard is should be noted, however, that theparameters of the UHMWPE used in the sealing layer need not be the sameas the parameters of the UHMWPE used in the reinforcing layers.

Since the sealing layer is intended to provide a sealing function, thesealing layer should be provided in the form of a film which issubstantially impermeable to the transported fluids. Thus, the highlyoriented UHMWPE needs to be provided in a form which has satisfactorysealing properties. These products are usually provided in the form of asolid block which can be further processed in order to obtain thematerial in the required form. The film may be produced by skiving athin film off the surface of the solid block. Alternatively the filmsmay be blown films of UHMWPE.

Suitable fluoropolymers include polytetrafluoroethylene (PFTE); afluorinated ethylene propylene copolymer, such as a copolymer ofhexafluoropropylene and tetrafluoroethylene(tetrafluoroethylene-perfluoropropylene) available from DuPontFluoroproducts under the trade name Teflon FEP; or a fluorinatedhydrocarbon—perfluoralkoxy—available from DuPont Fluoroproducts underthe trade name Teflon PFA. These films may be made by extrusion or byblowing.

Preferably, the sealing layer comprises a plurality of layers of each ofthe polymeric films. In an embodiment, the layers may be arranged sothat the first and second polymers alternate through the thickness ofthe sealing layer. However, this is not the only possible arrangement.In another arrangement all the layers of the first polymer may besurrounded by all the layers of the second polymer, or vice versa.

We prefer that the polymeric films of the sealing layer are formed of asheet of material which has been wound into a tubular form by windingthe sheet material in a helical manner. Each polymeric film may comprisea single continuous sheet which is wrapped around the inner reinforcinglayer from one end of the hose to the other. However, more usually (anddepending on the length of the hose) a plurality of separate lengths ofthe polymeric film would be wound around the inner reinforcing layer,each length of film covering a part of the length of the hose. Ifdesired the sealing layer may comprise at least two heat shrinkablesealing sleeves (i.e. tubular in form) which are arranged over the innerreinforcing layer. At least two of the sleeves should be made of adifferent material.

The sealing layer comprises at least two different films and these arepreferably arranged in an overlapping relationship. It is preferred thatthe sealing layer comprises least 5 overlapping layers, more preferablyat least 10 overlapping layers. In practice, the sealing layer maycomprise 20, 30, 40, 50, or more overlapping layers of film. The upperlimit for the number of layers depends upon the overall size of thehose, but it is unlikely that more than 100 layers would be required.Usually, 50 layers, at most, will be sufficient. The thickness of eachlayer of film would typically be in the range 50 to 100 micrometers. Thelayers will be made up of at least two different types of polymericfilm.

It will, of course, be appreciated that more than one sealing layer maybe provided.

Preferably, the sealing layer further comprises at least one layerpartially or entirely comprising a metal, a metal oxide or a mixturethereof. In this specification references to metal containing filmsincludes metal oxide containing films, unless stated otherwise. Thus,the metal layer may be a layer of metallic film (i.e. a separate layerconsisting substantially entirely of a metal, a metal oxide or a mixturethereof), or a polymer coated metallic film or a metallised polymerfilm. We prefer that the metal layer is a polymer coated metallic film.The metal may be, for example, aluminium oxide. The polymer may be, forexample, a polyester.

Suitable polymer coated metal films include the films available fromHiFi Industrial Film, of Stevenage, England, under the trade namesMEX505, MET800, MET800B and MET852; MET800B is preferred.

A further metal layer may be disposed outwardly of the sealing layer.Preferably, the further metal layer is disposed between the tubular bodyand the outer gripping member. Rockwool layers may also be provided hereto improve the thermal insulation, preferably between the sealing layerand the outer metal layer—the aim of this is to create a thermal annulusbetween the two metal layers.

According to another aspect of the invention there is provided a hosecomprising a tubular body of flexible material arranged between innerand outer gripping members, the tubular body comprising a sealing layersandwiched between an inner and an outer reinforcing layer,characterised in that the sealing layer comprises an UHMWPE. Thepreferred parameters of the UHMWPE (molecular weight range, etc)discussed above in relation to the reinforcing layers, are alsoappropriate to the sealing layer. In this regard is should be noted,however, that the parameters of the UHMWPE used in the sealing layerneed not be the same as the parameters of the UHMWPE used in thereinforcing layers.

In this aspect of the invention, if the sealing layer is formed of heatshrinkable sleeves, it is not essential for the sleeves to be made ofdifferent materials, but they must be made of UHMWPE.

In the most advantageous embodiment of the invention, the sealing layercomprises at least two polymeric films of different materials, and atleast one of the films comprises an ultra high molecular weightpolyethylene.

Preferably, the sealing layer further comprises at least one polymercoated metallic film or a metallised polymer film.

According to another aspect of the invention there is provided a hosecomprising a tubular body of flexible material arranged between innerand outer gripping members, the tubular body comprising a sealing layersandwiched between an inner and an outer reinforcing layer,characterised in that the sealing layer comprises at least one a layerof metallic film (i.e. a separate layer consisting substantiallyentirely of a metal, a metal oxide or a mixture thereof), or a polymercoated metallic film or a metallised polymer film.

The metal containing film is reflective and therefore reduces heat lossor heat gain—this is especially useful for cryogenic applications. Inaddition the metal containing film provides good barrier properties,thereby reducing vapour transmission—this is useful to prevent materialloss transporting gases.

When the hose is intended for cryogenic applications, then it isdesirable to provide insulation over the tubular body. The insulationcould be provided between the outer wire and the tubular member and/oroutside the outer wire. The insulation may comprise materialconventionally used to provided insulation in cryogenic equipment, suchas a synthetic foam material. One particularly suitable form ofinsulation is described below.

One aspect of the invention relates to improving the flexingcapabilities of the hose. Broadly, our invention involves providing ameans to hold the outer wires in position, without compromising theflexing abilities of the hose.

According to another aspect of the invention we provide a hosecomprising a tubular body of flexible material arranged between innerand outer gripping members, characterised by a cured resin matrixdisposed around the tubular body, the outer gripping members being atleast partially embedded in the resin matrix in order to restrictrelative movement between the outer gripping members and the rest of thehose.

The cured resin matrix must have sufficient flexibility to allow thehose to bend to the extent that is required for the specificapplications of the hose. Clearly, some applications may require moreflexibility than others.

The resin matrix preferably comprises a synthetic polymer, such aspolyurethane. It is especially preferred that the resin matrix is madeof a material that, prior to curing, is capable of being applied inliquid form to the hose. Typically, the uncured resin may be applied tothe hose by spraying, pouring or painting. This enables the uncuredresin to be applied over the outer surface of the tubular body and theouter gripping members, and then cured in-situ to form a solid, flexiblecoating. The mechanism of curing may be light, moisture, etc.

The resin matrix may bond to a layer under the outer gripping member andalso to any layer provided on the outer surface of the resin matrix. Itis preferred that at least one of the layers adjacent the cured resinmatrix is capable of withstanding cryogenic temperatures, so that, ifthe resin matrix cracks owing to the cryogenic temperatures, theadjacent layer holds the resin matrix together by virtue of the adhesionbetween the resin matrix and the adjacent layer. The most stablestructure is achieved when both sides of the resin matrix are bonded toadjacent layers.

We have also found that certain materials can provide hose withespecially good insulation, particularly at cryogenic temperatures, Inparticular, we have found that fabrics formed of basalt fibres provideparticularly good insulation.

Thus, according to another aspect of the invention we provide a hosecomprising a tubular body of flexible material arranged between innerand outer gripping members, and an insulation layer disposed around thetubular body, characterised in that the insulation layer includes afabric formed of basalt fibres.

Suitable basalt fibre fabrics are available from the Sudaglass FiberCompany under the trade designations BT-5, BT-8, BT-10, BT-11 and BT-13.The preferred thickness of the fabric is from about 0.1 mm up to about0.3 mm. If desired, a plurality of layers of the basalt fabric may beemployed.

We have also found that the insulation properties of basalt fabricsimprove under compression, therefore we prefer to provide a compressionlayer around the basalt fabric, which serves to compress the basaltlayer.

The insulation layer may further include layers made of other insulationmaterial, such as polymeric foams, in addition to the layer(s) of basaltfabric.

We prefer that the insulation layer further includes at least onereinforcement layer. The reinforcement layer may comprise a syntheticpolymer, such as a polyester, a polyamide or a polyolefin. Thereinforcement layer may be made of the same materials as the inner andouter reinforcing layers of the tubular body, which are described above.It is particularly preferred that the reinforcement layer of theinsulation layer is an ultra high molecular weight polyethylene(UHMWPE), such as DYNEEMA or SPECTRA, as described above.

The tubular body preferably comprises at least one reinforcing layer andat least one sealing layer. More preferably, there are at least tworeinforcing layers with the sealing layer sandwiched therebetween. Thetubular body preferably has the same features as the tubular bodydiscussed above.

The tubular body may further include one or more insulation layers madeof conventional insulation material and/or made of the basalt fibrefabric described above.

It is preferred that the hose is also provided with the axialstrengthening means as described above.

According to another aspect of the invention there is provided a methodof making a hose comprising:

-   -   (a) wrapping a wire around a tubular mandrel to form an inner        coil;    -   (b) wrapping a sheet material around the tubular mandrel and the        inner coil order to provide a tubular body formed of the sheet        material;    -   (c) wrapping a wire around the tubular body to form an outer        coil;    -   (d) applying a curable liquid resin over the outer surface of        the tubular body and the outer wire;    -   (e) allowing the resin to cure;    -   (f) securing the ends of the hose produced in step (e); and    -   (g) removing the hose from the mandrel.

Preferably, the method further comprises applying an insulation layerover the cured resin. The insulation layer preferably comprises a fabricformed of basalt fibres, as described above.

In step (c), the tubular body may comprise a tubular body as describedabove. In particular, the tubular body may include one or moreinsulation layers made of conventional insulation material and/or madeof the basalt fibre fabric described above.

The curing may take place simply by leaving the coated hose to stand inair, or may be effected, or accelerated, by an active means such asheating.

The cured resin matrix may contain gas bubbles, as described below.

Another aspect of the invention relates to improving the thermalresistance and/or buoyancy of hose. Broadly, this involves theutilisation of a layer comprising a plastics material having gas bubblesinjected therein.

According to another aspect of the invention we provide a hosecomprising a tubular body of flexible material arranged between innerand outer gripping members, characterised by layer of plastics materialaround the tubular member, the plastics material containing gas bubblestherein.

The plastics material is preferably a polyurethane. It is preferred thatthe plastics material is applied to the tubular body by spraying theplastics material, in liquid form, over the surface of the tubular body,then leaving it to cure. Again, the curing may take place simply byleaving the coated hose to stand in air, or may be effected, oraccelerated, by an active means such as heating.

The gas bubbles may be incorporated by injecting the gas into theplastics material, before spraying, while it is still in a liquid form.

The resultant layer of gas-containing plastics material has some of thebeneficial structural properties of the plastics material itself, suchas good wear and crush resistance, but also has substantially improvedinsulation properties. It also has improved buoyancy caused by thepresence of the gas, and can be used to produce a hose capable offloating in water and with evenly distributed buoyancy along its length.

Preferably the gas-containing plastics material is covered by a furtherlayer of plastics material, which does not contain any substantialamount of gas bubbles. Preferably this further layer of plasticsmaterial is bonded securely to the gas-containing layer. The furtherlayer of plastics material may be the same plastics material as thegas-containing layer. Preferably the further layer of plastics materialcomprises a polyurethane.

Both layers of plastics material can be applied by techniques other thanspraying, such as pouring, painting or extrusion.

Any suitable gas may be used to form the bubbles, including air,nitrogen or an inert gas.

The specific gravity of the polyurethane, prior to aeration, ispreferably approximately 1.2.

The hose typically has a specific gravity of around 1.8 without thegas-containing layer. Preferably the hose has an overall specificgravity of less than 1, preferably less than 0.8, after application ofthe gas-containing layer. The PU coating thickness may be, for example,about 4-8 mm, preferably about 6 mm. The gas bubbles are preferably lessthan about 2 mm in diameter.

The gas bubble containing layer also may be used in the embodiments ofhose described above. In particular the invention may include a layercomprising a cured resin matrix, as described above, in addition to agas containing layer. In this construction, the gas containing layerwould typically be disposed outwardly of the cured resin matrix. It ispossible for the gas containing layer to replace the cured resin matrix,such that the gas containing layer has the gripping members embeddedtherein to restrict relative movement of the outer gripping members.

According to another aspect of the invention there is provided a methodof making a hose comprising:

-   -   (a) wrapping a wire around a tubular mandrel to form an inner        coil;    -   (b) wrapping a sheet material around the tubular mandrel and the        inner coil order to provide a tubular body formed of the sheet        material;    -   (c) wrapping a wire around the tubular body to form an outer        coil;    -   (d) applying an curable aerated liquid resin over the outer        surface of the tubular body and the outer wire;    -   (e) allowing the resin to cure to form a solid plastics coating        containing gas bubbles therein;    -   (f) securing the ends of the hose produced in step (e); and    -   (g) removing the hose from the mandrel.

The term aerated is used to mean that the resin has been charged with agas, whereby, upon curing, the resin forms a solid material containinggas bubbles therein. As described above, the gas may be, but need notnecessarily be, air.

According to another aspect of the invention there is provided an endfitting for terminating an end of a hose comprising a tubular body offlexible material arranged between inner and outer helical wires,characterised in that the end fitting comprises: an inner member adaptedto be disposed at least partially within the hose; a sealing memberadapted to seal at least part of the tubular body between the sealingmember and the inner member; and a separate load transferring meansadapted to transfer axial loads applied to the hose around the sealingmember in order to reduce, or eliminate, the axial load on the hosebetween the sealing member and the inner member.

Preferably the sealing member is adapted to seal at least part of thetubular body fully around the circumference between the sealing memberand the inner member.

The inner member is preferably substantially cylindrical, and thesealing member is preferably in the form of a ring adapted to receivethe inner member therein, so that the tubular body can be clampedbetween the outer surface of the inner member and the inner surface ofthe ring.

The sealing between the sealing member and the inner member can beachieved in a number of ways. For example, in one embodiment, thesealing member may be provided in the form of a split ring which can betightened to provide an adequate seal. In another embodiment, thesealing member may simply comprise a sealing ring which is aninterference fit with the inner member.

However, in the preferred embodiment, the sealing member comprises aninner sealing ring and an outer split ring which can be tightened inorder to force the sealing ring into engagement with the tubular bodyand the inner member. In this embodiment it is preferred that thesealing ring is an interference fit with the inner member, in order tofurther improve the sealing.

The inner member, the sealing ring and the split ring may be anysuitable material. Typically, the inner member and the split ring wouldbe made of stainless steel. The sealing ring could be made of stainlesssteel, but it is preferred that it is made of polytetrafluoroethylene(PTFE).

The sealing member preferably has the features of the sealing memberdescribed hereinafter.

The load transferring means preferably comprises a hose engaging member,a load transmitting member and an end member secured to the innermember. The arrangement is such that the sealing member is disposedbetween the load transmitting member and the end member, and that thehose engaging member and the end member are connected through the loadtransmitting member.

The hose engaging member is adapted to engage the hose in such a mannerthat at least part of the axial forces within the hose are transferredfrom the hose to the hose engaging member. The hose engaging membertransfers these forces to the load transferring member, and the loadtransferring member transfers these forces to the end member. In thisway, at least part of the axial forces in the hose bypass the sealingmember, thereby improving the reliability of the seal provided by thesealing member.

It is preferred that the inner member and the load transferring meansinclude a portion configured to receive the wires of the hose. The innermember can be provided with helical recesses adapted to receive theinner wire therein, and the load transferring means can be provided withhelical recesses adapted to receive the outer wire therein. Preferably,it is the hose engaging member of the load transferring means which isprovided with the helical recesses.

The load transferring member preferably comprises a load transferringplate, which is typically disk shaped, having an aperture adapted toreceive the hose therethrough; plate has a surface engageable with thehose engaging member, whereby loads can be transferred from the hoseengaging member to the plate. The load transferring member preferablyfurther includes a load transferring rod secured between the plate andthe end member for transferring loads from the plate to the end member.A tightening member, such as a nut, can be provided on the rod.

The inner member preferably has a hose end which is adapted to extendwithin an end portion of the hose, and a tail end remote from the hoseend. The end member is arranged on one side of the sealing member,adjacent the tail end, and the hose engaging member is arranged on theother side of the sealing member adjacent the hose end.

Preferably the outer surface of the inner member is provided with atleast one formation thereon which is adapted to engage said part of thetubular member, below the sealing ring. The or each formation acts toimprove the seal of the tubular member and to make it more difficult forthe tubular member to be pulled from between the inner member and thesealing ring. It is preferred that the or each formation comprises aprojection extending circumferentially around the outer surface of theinner member. Desirably, there are two or three of said formations.

According to another aspect of the invention there is provided a methodof making a hose comprising:

-   -   (a) wrapping a wire around a tubular mandrel to form an inner        coil;    -   (b) wrapping a sheet material around the tubular mandrel and the        inner coil order to provide a tubular body formed of the sheet        material;    -   (c) wrapping a wire around the tubular body to form an outer        coil; and    -   (d) removing the hose from the mandrel; characterised by the        following steps:    -   (e) disposing an inner member in an open end of the hose;    -   (f) clamping a load transferring means to an outer surface of        the hose; and    -   (g) clamping a sealing member to an outer surface of the tubular        body.

Preferably the method further includes the following step between step(b) and (c):

-   -   (h) pulling a tubular axial strengthening member over a free end        of the mandrel, so that the mandrel extends within the axial        strengthening member, then pulling the axial strengthening        member along the mandrel so that it at least partially covers        the tubular body.

Preferably, the axial strengthening member is clamped by the loadtransferring means, and the method further includes the following stepafter step (f):

-   -   (i) folding back the tubular axial strengthening member over a        part of the load transferring means.

Preferably the coils and the sheet material are applied under tension inorder to provide the hose with good structural integrity.

Preferably the sheet material in step (b) comprises two reinforcinglayers sandwiching a sealing layer, as described above. In the preferredembodiment, an inner reinforcing layer, in sheet form, is wrappedhelically around the inner coil and the mandrel; then the sealing layer,in sheet form, is wrapped helically around the inner reinforcing layer;then the outer reinforcing layer, in sheet form, is wrapped around thesealing layer. Usually a plurality of sealing layers would be applied.

Preferably the inner and outer coils are applied in a helicalconfiguration having the same pitch, and the position of the coils ofthe outer coil are positioned half a pitch length offset from theposition of the coils of the inner coil.

It is possible for the hose to be removed from the mandrel before theend fitting is disposed within it. Alternatively, the end fitting can bedisposed within the rest of the hose by sliding the inner mandreltherealong up to an end of the hose, then securing the rest of the hoseto the end fitting while the end fitting and the rest of the hose remainon the mandrel.

A separate end fitting may, of course, be applied to each end of thehose.

The present invention relates to an improvement in the sealing of theends of the hose.

According to another aspect of the invention there is provided an endfitting for sealing an end of a hose comprising a tubular body offlexible material arranged between inner and outer helically woundwires, characterised in that the end fitting comprises: an inner memberadapted to be disposed at least partially within the hose; and a sealingring adapted to seal at least part of the tubular body between thesealing ring and the inner member; wherein the sealing member comprisesa sealing ring and a compression member for compressing the sealing ringinto sealing engagement with said part of the tubular body, and thecompression member is tightenable against the sealing member in order toselectively increase or decrease the compression force of thecompression member against the sealing member

In one especially advantageous embodiment, the compression member istightenable against the sealing member in order to selectively increaseor decrease the compression force of the compression member against thesealing member

In another especially advantageous embodiment, the compression memberand the sealing ring are removably securable to the hose.

Thus, in accordance with the present invention there is no unrecoverableplastic deformation in the components of the end fitting.

Preferably, the compression member is adapted to compress the sealingring equally in all directions.

Preferably, the compression member is of adjustable diameter, andfurther comprises a tightening means which can apply a force to reducethe diameter of the compression member, thereby compressing the sealingring within the compression member. We prefer that the compressionmember comprises a split ring or a jubilee clip.

In a particularly preferred embodiment, the compression member is madeof a material which contracts less than the sealing ring when subjectedto cooling. This provides an advantageous way of making the hose, asdescribed below. The sealing ring and the compression member may be anysuitable material. There are a number of materials which have thedesired difference in contraction under cooling. We prefer that thecompression member is stainless steel and the sealing ring ispolytetrafluoroethylene (PTFE). More preferably, the sealing ringcomprises reinforced PTFE, such as glass filled PTFE, as this helps toprevent creep. The sealing ring preferably comprises 10 to 20 wt % ofthe glass filling.

It is preferred that the inner member is made of a material whichcontracts less than the sealing ring when subjected to cooling. Thisfeature has the effect that when the end fitting is cooled, the sealingring contracts more than the inner member, thereby tightening the gripof the sealing ring on the inner member, and improving the seal. Theinner member may be made of any suitable material. Stainless steel hasbeen found to be particularly suitable.

Preferably the outer surface of the inner member is provided with atleast one formation thereon which is adapted to engage said part of thetubular member, below the sealing ring. The or each formation stretchesthe film, which acts to improve the seal of the tubular member and tomake it more difficult for the tubular member to be pulled from betweenthe inner member and the sealing ring; the stretching makes a more evenand smoother film surface under the seal. It is preferred that the oreach formation comprises a projection extending circumferentially aroundthe outer surface of the inner member. Desirably, there are two or threeof said formations.

It is preferred that the sealing ring is an interference fit with theinner member.

In a preferred embodiment, the end fitting further comprises a loadtransferring means as described above.

According to another aspect of the invention there is provided a hosecomprising a tubular body of flexible material arranged between an innerand an outer helically wound wire, the tubular body serving to transportfluid through the hose and to prevent fluid leakage through the body,characterised in that the hose further comprises an end fitting asdescribed above.

The hose engaging member may transfer loads from the hose simply byvirtue of the frictional forces between the hose and the hose engagingmember. However, it is preferred that the hose engaging member isadapted to secure a part of the hose which is folded back over an outerpart of the hose engaging member. This arrangement makes it possible forthe folded part of the hose to transmit loads to the hose engagingmember. The folded part of the hose may be part of the tubular body, butit is preferably an axial strengthening means in the form of a braid, asdescribed below.

The tubular body preferably comprises at least one reinforcing layer andat least one sealing layer. More preferably, there are at least tworeinforcing layers with the sealing layer sandwiched therebetween. Thetubular body preferably has the same features as the tubular bodydiscussed above.

The tubular body may further include one or more insulation layers madeof conventional insulation material and/or made of the basalt fibrefabric described above.

It is preferred that the hose is also provided with the axialstrengthening means as described above.

According to another aspect of the invention there is provided a methodof making a hose comprising:

-   -   (a) wrapping a wire around a tubular mandrel to form an inner        coil;    -   (b) wrapping a sheet material around the tubular mandrel and the        inner coil order to provide a tubular body formed of the sheet        material;    -   (c) wrapping a wire around the tubular body to form an outer        coil; and    -   (d) removing the hose from the mandrel; characterised by the        following steps:    -   (e) disposing an inner member in an open end of the hose;    -   (f) applying a sealing ring over an outer surface of the tubular        body; and    -   (g) applying a compression member over the sealing ring, and        compressing the sealing member into sealing engagement with the        tubular member and the inner member using the compression        member.

Preferably, the compression member is made from a material whichcontracts less than the sealing ring when subjected to cooling.Preferably also, the compression member includes a means for adjustingthe compressive force applied to the sealing ring; a split ring isparticularly suitable for use as the compression member. Thisarrangement makes possible a particularly preferred manufacturingprocess.

In this process, the compression member is applied to the sealing ringand tightened, then the compression member and sealing ring aresubjected to at least one cooling cycle. This causes the sealing memberto contract relative to the compression member, whereby the compressiveforce applied by the compression member is reduced. While the cooling ismaintained, the compressive force applied by the compression member isthen readjusted to bring it back to approximately the same level asbefore the cooling, and then the temperature is increased. This cyclemay be applied as many times as desired. It is preferred that thecooling cycle is applied at least two or three times and that each timethe end fitting is cooled to temperatures at least 5° C. below theintended operating temperature of the hose. This technique has threeimportant benefits.

First, if the hose is operated at temperature above the coolingtemperature, then the sealing ring will receive additional compressionfrom the compression member by virtue of the thermal expansion of thesealing member which will take place after the cooling is removed.

Second, the hose will have substantial seal energisation at temperaturesat least as low as the cooling temperature. This is particularly usefulwhen the hose is to be used in cryogenic applications. Thus, thetemperature to which the hose is cooled is preferably as low as thetemperature to which the hose will be subjected in the use for which itis intended. In general, we prefer that the cooling temperature is −50°C. or less, more preferably −100° C. or less, and still more preferably−150° C. or less. Preferably, the cooling is carried out with liquidnitrogen, whereby the cooling temperature can be as low as about −196°C.

Third, the possibility of creep failure is much reduced, or eveneliminated, by utilising the hydrostatic stress provided by thecompression member.

We prefer that the inner member is made of a material which contractsless than the sealing ring when subjected to cooling. This has theeffect that cooling the end fitting causes the sealing ring to grip theinner member more tightly, thereby improving the sealing of the endfitting when the hose is operated at low temperatures.

Preferably the coils and the sheet material are applied under tension inorder to provide the hose with good structural integrity.

Preferably the sheet material in step (b) comprises two reinforcinglayers sandwiching a sealing layer, as described above. In the preferredembodiment, an inner reinforcing layer, in sheet form, is wrappedhelically around the inner coil and the mandrel; then the sealing layer,in sheet form, is wrapped helically around the inner reinforcing layer;then the outer reinforcing layer, in sheet form, is wrapped around thesealing layer. Usually a plurality of sealing layers would be applied.

Preferably the inner and outer coils are applied in a helicalconfiguration having the same pitch, and the position of the coils ofthe outer coil are positioned half a pitch length offset from theposition of the coils of the inner coil.

It is possible for the hose to be removed from the mandrel before theend fitting is disposed within it. Alternatively, the end fitting can bedisposed within the rest of the hose by sliding the inner mandreltherealong up to an end of the hose, then securing the rest of the hoseto the end fitting while the end fitting and the rest of the hose remainon the mandrel.

In the above described aspects of the invention, the gripping memberstypically each comprise a helically wound wire. The helices of the wiresare typically arranged such that they are offset from one another by adistance corresponding to half the pitch of the helices. The purpose ofthe wires is to grip the tubular body firmly therebetween to keep thelayers of the tubular body intact and to provide structural integrityfor the hose. The inner and outer wires may be, for example, mild steel,austenitic stainless steel or aluminium. If desired, the wires may begalvanised or coated with a polymer.

It will be appreciated that although the wires making up the grippingmembers may have a considerable tensile strength, the arrangement of thewires in coils means that the gripping members can deform when subjectedto relatively small axial tension. Any significant deformation in thecoils will quickly destroy the structural integrity of the hose.

The hose according to the invention can be provided for use in a widevariety of conditions, such as temperatures above 100° C., temperaturesfrom 0° C. to 100° C. and temperatures below 0° C. With a suitablechoice of material, the hose can be used at temperatures below −20° C.,below −50° C. or even below −100° C. For example, for LNG transport, thehose may have to operate at temperatures down to −170° C., or evenlower. Furthermore, it is also contemplated that the hose may be used totransport liquid oxygen (bp −183° C.) or liquid nitrogen (bp −196° C.),in which case the hose may need to operate at temperatures of −200° C.or lower.

The hose according to the invention can also be provided for use at avariety of different duties. Typically, the inner diameter of the hosewould range from about 2 inches (51 mm) to about 24 inches (610 mm),more typically from about 8 inches (203 mm) to about 16 inches (406 mm).In general, the operating pressure of the hose would be in the rangefrom about 500 kPa gauge up to about 2000 kPa gauge, or possibly up toabout 2500 kPa gauge. These pressures relate to the operating pressureof the hose, not the burst pressure (which must be several timesgreater). The volumetric flow rate depends upon the fluid medium, thepressure and the inner diameter. Flowrates from 1000 m³/h up to 12000m³/h are typical.

The hose according to the invention can also be provided for use withcorrosive materials, such as strong acids,

Reference is now made to the accompanying drawings, in which:

FIG. 1 is a schematic diagram showing the principle stresses to whichthe hose according to the invention may be subjected in operation;

FIG. 2 is a schematic cross-sectional view of a hose according to theinvention;

FIG. 3 is a sectional view showing the arrangement of a reinforcinglayer of the hose according to the invention;

FIG. 4A is a sectional view showing the arrangement of a tubular axialstrengthening sheath of the hose according to the invention, the axialstrengthening sheath being in a relaxed condition;

FIG. 4B is a sectional view showing the arrangement of a tubular axialstrengthening sheath of the hose according to the invention, the axialstrengthening sheath being in a tightened condition;

FIGS. 5A, 5B, 5C and 5D show four applications of hose according to thepresent invention;

FIG. 6 is a cross-sectional view showing the a sealing layer of a hoseaccording to the invention;

FIG. 7 is a cross-sectional view showing an insulation layer of the hoseof FIG. 2; in greater detail; and

FIG. 8 is a schematic cross sectional view of an end fitting for a hose,according to the invention.

FIG. 9 is a cross-sectional view showing another embodiment of theinsulation layer of the hose.

FIG. 1 shows the stresses to which a hose H is normally subjected toduring use. The hoop stress is designated by the arrows HS and is thestress that acts tangentially to the periphery of the hose H. The axialstress is designated by the arrows AS and is the stress which actsaxially along the length of the hose H. The flexing stress is designatedFS and is the stress which acts transverse to the longitudinal axis ofthe hose H when it is flexed. The torsional stress is designated TS andis a twisting stress which acts about the longitudinal axis of the hose.The crushing stress is designated CS and results from loads appliedradially to the exterior of the hose H.

The hoop stress HS is generated by the pressure of the fluid in the hoseH. The axial stress AS is generated by the pressure of the fluid in thehose and also by the combination of the weight of the fluid in the hoseH and by the weight of the hose H itself. The flexing stress FS iscaused by the requirement to bend the hose H in order to position itproperly, and by movement of the hose H during use. The torsional stressTS is caused by twisting of the hose. Prior art hose is generallycapable of withstanding the hoop stresses HS, the flexing stresses FSand the torsional stresses TS, but is less capable of withstanding theaxial stresses AS. For this reason, when prior art hoses were subjectedto large axial stresses AS they generally had to be supported, tominimise the axial stresses AS.

The problem of withstanding the axial stresses AS has been solved by thepresent invention. In FIG. 2 a hose in accordance with the invention isgenerally designated 10. In order to improve the clarity the winding ofthe various layers in FIG. 2, and in the other Figures, has not beenshown.

The hose 10 comprises a tubular body 12 which comprises an innerreinforcing layer 14, an outer reinforcing layer 16, and a sealing layer18 sandwiched between the layers 14 and 16. A generally tubular sheath20, which provides axial strengthening, is disposed around the outersurface of the outer reinforcing layer 16.

The tubular body 12 and the tubular sheath 20 are disposed between aninner helically coiled wire 22 and an outer helically coiled wire 24.The inner and outer wires 22 and 24 are disposed so that they are offsetfrom one another by a distance corresponding to half the pitch length ofthe helix of the coils.

An insulation layer 26 is disposed around the outer wire 24. Theinsulation layer may be a conventional insulating material, such as aplastics foam, or may be a material described below in relation to FIG.7.

The reinforcing layers 14 and 16 comprise woven fabrics of a syntheticmaterial, such as UHMWPE or aramid fibres. FIG. 3 illustrates the innerreinforcing layer 14, from which it will be clear that the innerreinforcing layer 14 comprises fibres 14 a arranged in a warp directionW, and fibres 14 b arranged in a weft direction F. In FIG. 3 only thelayer 14 has been shown, in order to improve the clarity. We haveunexpectedly found that the axial strength of the hose 10 can beimproved by arranging the inner reinforcing layer 14 such that the warpdirection W is at a low angle, of less than 20° and typically around 15°to the longitudinal axis of the hose 10. This angle is indicated by thesymbol α in FIG. 3. The structure and orientation of the outerreinforcing layer 16 is substantially identical to the inner reinforcinglayer 14; the angle α for the outer reinforcing layer 16 may be the sameas, or different from, the angle α for the inner reinforcing layer 14.

The sealing layer 18 comprises a plurality of layers of plastics filmwhich are wrapped around the outer surface of the inner reinforcinglayer 14 to provide a fluid tight seal between the inner and outerreinforcing layers 14 and 16.

The hose 10 further includes a reinforcing layer disposed between thesheath 20 and the outer wires 24. The reinforcing layer may have similarcharacteristics to the sheath 20 and the tubular body 12.

The tubular sheath 20 is formed of two sets of fibres 20 a and 20 bwhich are braided to form a tubular braid. This is shown in FIGS. 4A and4B in these Figures only the tubular sheath 20 has been shown, in orderto improve the clarity. There are spaces 28 between the sets of fibres20 a and 20 b, so that when the tubular sheath 20 is subjected to axialtensioning the fibres 20 a and 20 b can contract moving into the spaces28. This acts in a way to try to reduce the diameter of the tubularsheath 20, which causes it to tighten around the tubular body 12,thereby increasing the structural integrity and burst pressure of thehose 10. FIG. 4B shows the tubular sheath 20 in the tightened condition.

The sealing layer 18 is shown in greater detail in FIG. 6. The provisionof the sealing layer 18 improves the resistance of hose to the flexingstress FS and the hoop stress HS.

As shown in FIG. 6, the sealing layer 18 comprises a plurality of layers18 a of a film made of a first polymer (such as a highly orientedUHMWPE) interleaved with a plurality of layers 18 b of a film made of asecond polymer (such as PFTE or FEP), the two polymers having adifferent stiffness. The layers 18 a and 18 b have been wrapped aroundthe outer surface of the inner reinforcing layer 14 to provide a fluidtight seal between the inner and outer reinforcing layers 14 and 16. Asmentioned above, the layers 18 a and 18 b do not necessarily have to bearranged in an alternative fashion. For example, all the layers 18 acould be arranged together, and all the layers 18 b could be arrangedtogether.

The insulation layer 26 is shown in greater detail in FIG. 7 shows theinsulation layer 26 in greater detail. The insulation layer is primarilyconcerned with improving the resistance of hose to the flexing stressFS, and with insulating the hose.

The insulation layer 26 comprises an inner layer 26 a which is formed ofa polyurethane which has been sprayed, poured, or otherwise applied,over the tubular body 12 and the outer wire 24. After hardening, thepolyurethane layer 26 a forms a solid matrix within which the outer wire24 is embedded. This helps to keep the outer wire 24 fixed in position.In a preferred embodiment, the inner layer 26 a is provided with airbubbles therein.

The insulation layer 26 includes a layer 26 b over the layer 26 a. Thelayer 26 b comprises a fabric formed of basalt fibres. The layer 26 bprovides most of the insulating properties of the hose 10.

The insulation layer 26 further includes a layer 26 c over the layer 26b. The layer 26 c comprises an UHMWPE such as DYNEEMA or SPECTRA. Thepurpose of the layer 26 c is primarily to provide strengthening againsthoop and flexing stresses.

The insulation layer 26 further includes a compression layer 26 d. Thepurpose of the compression layer 26 d is to compress the layer 26 b, aswe have found that the insulation properties of the basalt fabric layer26 b are much improved under compression. The compression layer 26 dmay, for example, comprise a rope or cord which is wrapped tightlyaround the layer 26 c. Preferably, the compression layer 26 d comprisesan axial strengthening sheath like the sheath 20 described above.

Referring to FIG. 9, a further polyurethane layer 26 e containing gasbubbles 50 may be provided over the layer 26 d to further improve theinsulation properties and the buoyancy of the hose 10. A still furtherpolyurethane layer 51 not containing gas bubbles may be provided overthe gas-containing polyurethane layer. The further polyurethane layercould additionally, or instead, be provided within the layer 26 d. It isalso possible for the layer 26 a itself to contain the gas bubbles.

The hose 10 can be manufactured by the following technique. As a firststep the inner wire 22 is wound around a support mandrel (not shown), inorder to provide a helical arrangement having a desired pitch. Thediameter of the support mandrel corresponds to the desired internaldiameter of the hose 10. The inner reinforcing layer 14 is then wrappedaround the inner wire 22 and the support mandrel, such that warpdirection W is set at the desired angle a.

A plurality of layers of the plastics films 18 a, 18 b making up thesealing layer 18 are then wrapped around the outer surface of the innerreinforcing layer 14. Usually, the films 18 a and 18 b would have alength substantially less than the length of the hose 10, so that aplurality of separate lengths of the films 18 a and 18 b would have tobe wound around the inner layer 14. The films 18 a and 18 b arepreferably arranged in an alternating fashion through the thickness ofthe sealing layer 18. Typically there might be five separate layers ofthe films 18 a and 18 b through the thickness of the sealing layer.

The outer reinforcing layer 16 is then wrapped around the sealing layer18, such that the warp direction W is set at the desired angle (whichmay be α, or may be some other angle close to α). The tubular axialstrengthening sheath 20 is drawn over the outside of the outerreinforcing layer 16. The further reinforcing layer is then wrappedaround the sheath 20.

The outer wire 24 is then wrapped around the further reinforcing layerin order to provide a helical arrangement having a desired pitch. Thepitch of the outer wire 24 would normally be the same as the pitch ofthe inner wire 22, and the position of the wire 24 would normally besuch that the coils of the wire 24 are offset from the coils of the wire22 by a distance corresponding to half a pitch length; this isillustrated in FIG. 2, where the pitch length is designated p.

A polyurethane resin is then be sprayed over the outer surface of thereinforcing layer to form a resin coating over the reinforcing layer andthe outer wire 24. The resin may then be left to harden, in order toform the layer 26 a. The resin may be aerated before hardening(typically before spraying or painting) to provide gas bubbles therein.The basalt fabric layer 26 b is then wrapped around the polyurethanelayer 26 a, and the UHMWPE layer 26 c is then wrapped around the layer26 b. Finally, the compression layer 26 d is applied over the layer 26c.

The ends of the hose 10 may be sealed by crimping a sleeve onto aninsert inside the hose 10. This termination is generally applied afterthe hose 10 as been removed from the mandrel.

The ends of the hose 10 may be sealed using the end fitting 200 shown inFIG. 8. In FIG. 8, the hose 10 has not been shown, in order to improvethe clarity. The end fitting 200 comprises a tubular inner member 202having a hose end 202 a and a tail end 202 b. The end fitting 200further includes a sealing member which comprises a PTFE sealing ring204 and a stainless steel split ring 206 around the PTFE sealing ring204.

The end fitting 200 further includes a load transferring means comprisesa hose engaging member 208, a load transferring member 210 and an endmember in the form of a disk-shaped plate 212. The load transferringmember comprises a disk-shaped plate 214 and at least one loadtransferring rod 216. In FIG. 2 there are two of the rods 216, but it ispossible to provide three or more of the rods 216. A tightening nut 218is provided on each rod 216. The plates 212 and 214 have apertures 212 aand 214 a respectively for receiving the rods 216.

The plates 212 and 214 may each be a Simonplate, the hose engagingmember 202 may be a Gedring and the split ring 206 may be an Ericring.

The plate 212 is further provided with apertures 212 b, and the tail end202 b of the inner member 202 is provided with apertures 202 c. Fixingbolts 220 extend through the apertures 202 b and 212 b to secure theplate 212 to the tail end 202 a of the inner member 202. In FIG. 2,there are two fixing bolts 220 and associated apertures, but it will beappreciated that fewer, or more, fixing bolts 220 and associatedapertures could be provided.

The hose engaging member 208 is provided with an inner helical recess inthe form of grooves 208 a which are adapted to receive the outer wire 24of the hose 10 therein. The inner member 202 is provided with an outerhelical recess in the form of grooves 202 d which are adapted to receivethe inner wire 22 therein. It will be seen from FIG. 2 that, like theinner and outer wires 22 and 24, the grooves 208 a and 202 d are spacedby half a pitch length p.

The inner member 202 is provided with two circumferential projections202 e which are located under the sealing ring 204. The projections 202e serve the improve the sealing of the tubular member 20 between theinner member 202 and the sealing ring 204, and help to prevent thetubular member from inadvertently being pulled out of position.

The hose 10 is secured to the end fitting 200 as follows. The innermember 202 is threaded into the end of the hose 10, so that the hose 10lies close to the plate 212. The inner wire 22 is received in thegrooves 202 d and the outer wire 24 is received in the grooves 208 a.The inner and outer wires 22 and 24 are cut back so that they do notextend along the inner member 202 beyond the grooves 202 d and 208 a.The insulation 26 is also cut back to this point. The inner reinforcinglayer 14 is also cut back at this point, or at some point before theinner reinforcing layer 14 reaches the sealing ring 204. This means thatthe sealing layer 18 directly engages the outer surface of the innermember 202. The rest of the tubular body 12, however, is allowed toextend along the inner member 202 between the inner member 202 and thesealing ring 204.

The hose engaging member 208 is then tightened to cause it to clamp downon the hose 10 bring it into firm engagement with the hose 10. The nuts218 are then tightened, which induces some axial tension in the hose 10,thereby taking up any play in the system. These forces are transmittedfrom the hose engaging member 208, to the plate 214, to the rod 216, tothe plate 212, and to the tail end 202 b of the inner member 202. Thetubular member 20 is pulled back over the upper surface of the hoseengaging member 208, and is secured to projections 208 b extending fromthe upper surface of the hose engaging member 208.

The tubular body 12 extends under the sealing ring 204. After the hoseengaging member 208 and the nuts 218 have been tightened, the split ring206 is tightened in order to increase the force applied on the tubularbody 12 by the sealing ring 204.

The end fitting 200 is then cooled to a low temperature by liquidnitrogen. This causes the sealing ring 204 to contract relatively morethan the split ring 206, whereby the compressive force applied on thesealing ring 204 by the split ring 206 is reduced. While the split ring206 and the sealing ring 204 are at a relatively low temperature, thesplit ring 206 is again tightened. The temperature is then allowed torise to ambient conditions, whereby the compressive force on the sealingring increases by virtue of the greater expansion of sealing ring 204relative to the split ring 206.

This completes the end fitting for the hose 10. The hose engaging member208 provides some sealing of the end of the hose 208, and helps to takeaxial forces in the hose 10 around the sealing ring 204. The sealingring 204 provides the remainder of the sealing of the hose 10.

FIGS. 5A to 5D show three applications for the hose 10. In each of FIGS.5A to 5C a floating production, storage and offloading vessel (FPSO) 102is linked to a LNG carrier 104 by means of a hose 10 according to theinvention. The hose 10 carries LNG from a storage tank of the FPSO 102to a storage tank of the LNG carrier 104. In FIG. 5A, the hose 10 liesabove the sea level 106. In FIG. 5B, the hose 10 is submerged below thesea level 106. In FIG. 5C, the hose 10 floats near the surface of thesea. In each case the hose 10 carries the LNG without any intermediatesupport. In FIG. 5D the LNG carrier is linked to a land-based storagefacility 108 via the hose 10.

The hose 10 may be used for many other applications apart from theapplications shown in FIGS. 5A to 5C. The hose may be used in cryogenicand non-cryogenic conditions.

It will be appreciated that the invention described above may bemodified. For example, the tubular sheath 20 could be located outsidethe outer wire 24. Also, the hose 10 may include additional reinforcinglayers 14,18, sealing layers 16 and/or tubular sheaths 20. One or moreof, or even all of, the sealing layers 18 a may be a polymer coatedmetallic film, or metallised polymer film. Similarly, one or more of, oreven all of, the sealing layers 18 b may be a polymer coated metallicfilm or metallised polymer film.

1. An end fitting for terminating an end of a hose comprising a tubularbody of flexible material arranged between inner and outer grippingmembers, wherein the end fitting comprises: an inner member adapted tobe disposed at least partially within the hose; a sealing member adaptedto seal at least part of the tubular body fully around the circumferencebetween the sealing member and the inner member; and a separate loadtransferring means adapted to transfer axial loads between the hose andthe inner member in such a manner that said axial loads are divertedaround the sealing member in order to reduce, or eliminate, the axialload on the hose between the sealing member and the inner member,wherein the sealing member is adapted to seal against the tubular bodyindependently of the application of axial loads between the hose and theinner member, and wherein the sealing member comprises an inner sealingring and an outer split ring which can be tightened in order to forcethe sealing ring into engagement with the tubular body and the innermember.
 2. An end fitting according to claim 1, wherein the inner memberis substantially cylindrical, and the sealing member is in the form of aring adapted to receive the inner member therein, so that the tubularbody can be clamped between the outer surface of the inner member andthe inner surface of the ring.
 3. An end fitting according to claim 1,wherein the split ring is stainless steel and the sealing ring ispolytetrafluoroethylene.
 4. An end fitting according to claim 1, whereinthe load transferring means comprises a hose engaging member, a loadtransmitting member and an end member secured to the inner member, thearrangement being such that the sealing member is disposed between theload transmitting member and the end member, and that the hose engagingmember and the end member are connected through the load transmittingmember.
 5. An end fitting according to claim 4, wherein the hoseengaging member is adapted to engage the hose in such a manner that atleast part of the axial forces within the hose are transferred from thehose to the hose engaging member.
 6. An end fitting according to claim4, wherein the inner member and the hose engaging member each include aportion configured to receive the inner and outer wires of the hose. 7.An end fitting according to claim 1, wherein the inner member has a hoseend which is adapted to extend within an end portion of the hose, and atail end remote from the hose end, and wherein an end member is arrangedon one side of the sealing member, adjacent the tail end, and the hoseengaging member is arranged on the other side of the sealing memberadjacent the hose end.
 8. An end fitting for terminating an end of ahose comprising a tubular body of flexible material arranged betweeninner and outer gripping members, wherein the end fitting comprises: aninner member adapted to be disposed at least partially within the hose;a sealing member adapted to seal at least part of the tubular body fullyaround the circumference between the sealing member and the innermember; and a separate load transferring means adapted to transfer axialloads between the hose and the inner member in such a manner that saidaxial loads are diverted around the sealing member in order to reduce,or eliminate, the axial load on the hose between the sealing member andthe inner member, wherein the sealing member is adapted to seal againstthe tubular body independently of the application of axial loads betweenthe hose and the inner member, wherein the load transferring meanscomprises a hose engaging member, a load transmitting member and an endmember secured to the inner member, the arrangement being such that thesealing member is disposed between the lead transmitting member and theend member, and that the hose engaging member and the end member areconnected through the load transmitting member, and wherein the loadtransferring member comprises a load transferring plate having anaperture adapted to receive the hose therethrough, the plate having asurface engageable with the hose engaging member, whereby loads can betransferred from the hose engaging member to the plate.
 9. An endfitting according to claim 8, wherein the load transferring memberfurther includes a load transferring rod secured between the plate andthe end member for transferring loads from the plate to the end member.10. A hose in combination with an end fitting, the hose comprising atubular body of flexible material arranged between inner and outergripping members, the tubular body serving to transport fluid throughthe hose and to prevent fluid leakage through the body, the end fittingbeing fitted to an end of the hose, wherein the end fitting comprises:an inner member adapted to be disposed at least partially within thehose; a sealing member adapted to seal at least part of the tubular bodyfully around the circumference between the sealing member an the innermember; and a separate load transferring means adapted to transfer axialloads between the hose and the inner member in such a manner that saidaxial loads are diverted around the sealing member in order to reduce,or eliminate, the axial load on the hose between the sealing member andthe inner member, wherein the sealing member is adapted to seal againstthe tubular body independently of the application of axial loads betweenthe hose and the inner member, and wherein the sealing member comprisesan inner sealing ring and an outer split ring which can be tightened inorder to force the sealing ring into engagement with the tubular bodyand the inner member.
 11. A hose according to claim 10, wherein the loadtransferring means comprises a hose engaging member, a load transmittingmember and an end member secured to the inner member, the arrangementbeing such that the sealing member is disposed between the loadtransmitting member and the end member, and that the hose engagingmember and the end member are connected through the load transmittingmember, wherein the hose engaging member is adapted to secure a part ofthe hose which is folded back over an outer part of the hose engagingmember.
 12. A hose according to claim 10, wherein the tubular bodyextends between the inner member and the sealing member.
 13. A hoseaccording to claim 10, wherein the tubular body comprises at least onereinforcing layer and at least one sealing layer.
 14. A hose accordingto claim 10, wherein the gripping members comprise helical wires.
 15. Ahose in combination with an end fitting, the hose comprising a tubularbody of flexible material arranged between an inner and an outerhelically wound wire, the tubular body serving to transport fluidthrough the hose and to prevent fluid leakage through the body, the endfitting being fitted to an end of the hose, wherein the end fittingcomprises: an inner member adapted to be disposed at least partiallywithin the hose; a sealing member adapted to seal at least part of thetubular body fully around the circumference between the sealing memberan the inner member; and a separate load transferring means adapted totransfer axial loads between the hose and the inner member in such amanner that said axial loads are diverted around the sealing member inorder to reduce, or eliminate, the axial load on the hose between thesealing member and the inner member, wherein the sealing member isadapted to seal against the tubular body independently of theapplication of axial loads between the hose and the inner member,wherein the load transferring means comprises a hose engaging member, aload transmitting member and an end member secured to the inner member,the arrangement being such that the sealing member is disposed betweenthe load transmitting member and the end member, and that the hoseengaging member and the end member are connected through the loadtransmitting member, wherein the hose engaging member is adapted tosecure a part of the hose which is folded back over an outer part of thehose engaging member, and wherein further comprising an axialstrengthening means in the form of a braid around the tubular body, andwherein the braid is the part of the hose that is folded back over theouter part of the tubular member.